The concept is simple. In a gallon size ziptop bag, you fill it half full with ice and 1/2c. rock salt.
In a quart size ziptop bag, you pour 1 c. half&half, 2T.sugar, and a dash of vanilla (or whatever flavor you like.)
You put the sealed quart bag into the gallon bag, close it up, and shake for 5 full minutes. My kiddos arms can’t really handle 5 minutes of shaking, so I sent them out to the trampoline to jump for 5 minutes!